"Comparing all the water sports I have done downwind foiling has been the hardest thing to learn. If you can foil surf and sup downwind the learning curve wont be as harsh. The hardest part is learning to un-weight the board to get started. Scotty and myself have done so many runs when we didnt even get up on the foil. Now its the only thing I want to do. Its so much fun!!!"

I call it retreating, but same thing. It is super important to et this timing right, or you will be working hard. I use the term retreating as you're kind of bailing on a good run (i.e. retreating). It is so hard to retreat/peel off when you're flying along and everything feels awesome! Here's a try an explaining how I try and time it.

1. Paddling and pumping for your bump.
2. If there's no chop or prop to get you up and the bumps seems like it's going to pass you by, let it go, slow down and regain energy. then hit the throttle again as you're coming off the back of it (very important), you kind of want your first paddle pump to be as the next bump is forming behind your board (don't wait too long or it will pass you too), it will feel a little dead and un-aided at first, but quickly become easy and get you foiling efficiently.
3. Once you get up on the foil and have gathered speed, it is time to start thinking about your first retreat. It is important to ensure you have speed, but do not wait too long. 99% of errors IMO are from staying on your pump for too long and drawing out the speed. As soon as your speed spikes, get off and use that speed to go hunting.
4. This is the tricky part, you will hardly be able to see what it is that you are going for (you will learn to read it really well the more you do it), but you need to turn for it early and align your momentum in a very similar fashion to point 2. (before the pump has reached you and properly formed). It will feel like your turning straight in the "pit", and your inner thoughts are going to be like WTF R U Doin! But it will all happen, the pump will form up behind you, and your speed will increase again, and if you've done it well you may not even have to bounce, pump or paddle at all. Then we repeat the process.
5. It is important to know when you can run some glides, and when you need to keep retreating, plus you need to watch and follow the swell/chop pattern, and there's often a repeating pattern out there where you'll go Right, right, Left, right, right, left (and so on). The important thing is not to reach and pass your top speed, if you start decelerating, you've likely stayed on that bump too long and will inevitably need to pump and/or paddle for your next transition. (If you constantly hunt after that 29km/h run DW'ing (which is what I used to do a lot), you will find your averages are low and efforts are through the roof. However if you come to the realisation that 19km/h is a smoking fast average, and 25km.h is a smoking high for DW'ing, then you'll have higher lows, better averages with less pumping and no paddling and use far less energy allowing you to go way further.)

I guess the key thing I always say, is do it way before you think you should. Retreat earlier, change bumps earlier, paddle earlier and so on. When you get in the groove, it is amazing, and will feel like you're floating on nothing at all but cruising at a good stable pace with little effort.

Don't be in a rush, learn to hold your foil back, fly high. I like using an 80cm mast for DW, and I use every cm. Slow, smooth and calculated.

Most of all, just get out there and do it. Every session you learn something.

I am 92kg and an older kind of paddler but a weekend 14 racer kind of guy. i say don't go longer than 7'6" or even 7'8". if you need stability or volume go wider. I have been working a few boards with "One" for me for downwinding here in the Gulf in SA and a little glide does help but any board longer than above just touches down too easy and makes foiling hard. Funny I see a lot of people go too short for downwinding too and not be able to learn so it's a balance for sure. Pure surfing is ok to go real short too (I have ridden a mates 5'10" sup in the surf and its fine). So keeping that in mind I'd say steer clear of the long boards.